Northstar Engines and System Technical Discussion Discussion, Northstar Maintenance -Tune Up in Cadillac Engine Discussion; I WANT TO CHANGE THE SPARK PLUGS ON MY CATERA BUT CAN'T SEE WHERE THEY ARE LOCATED...
DOES ANYONE HAVE ...

re: Northstar Maintenance -Tune Up

Hey guys what sensor needs to be cleaned if the idle is irregular at well... Idle? It goes from 800rpms to 400 and surges. I cleaned the throttle body did the plugs and wires as well. Running nice synthetic oil and got a good air filter on.

re: Northstar Maintenance -Tune Up

I too was looking up maintenance suggestions for the Northstar and you hit the nail on the head for my car. It got regular tune-ups twice a year before I bought it and it runs like a dream but developed a warning light for coolant. I parked it till my mechanic could inspect it. Stale coolant is an overlooked area. . For $300 they fixed the housing and flushed the system with new coolant. The car is running like a dream.
Maintenance lessons from 30 years ago are probably not relevant anymore. I am learning that.

re: Northstar Maintenance -Tune Up

Originally Posted by Omerus

Stale coolant is an overlooked area. . For $300 they fixed the housing and flushed the system with new coolant. The car is running like a dream. Maintenance lessons from 30 years ago are probably not relevant anymore. I am learning that.

re: Northstar Maintenance -Tune Up

Originally Posted by Omerus

I too was looking up maintenance suggestions for the Northstar and you hit the nail on the head for my car. It got regular tune-ups twice a year before I bought it.
Maintenance lessons from 30 years ago are probably not relevant anymore. I am learning that.

Boy, talk about "old school". Yes, some things are no longer relevant.

re: Northstar Maintenance -Tune Up

I think you can save your self a lot of time and energy and possibly money . Just start out with the block test and get it over with. If it passes then you can look for the easier less expensive stuff. My car never overheated, but it still had headgasket failure! I wasted a lot of time looking/hoping for the less expensive repair!

HOW TO: Change the spark plugs on a 96 VIN Y DeVille

There's a spark plug tutorial in the tech tips section, but some of us (like me) like pictures because they help show where stuff is, and sometimes ya just can't beat a picture. So here goes.

As far as tools go, a basic socket set (metric), a spark plug socket lined with rubber (INVALUABLE) and anti-seize compound is all that is needed. You may want some electrical tape.

Parts include 8 AC-Delco 41-950 plugs and I used the 748J wire set. Length is near factory specs, which is nice.

Pop the hood

Remove the strut brace bar that stretches across the back of the engine bay. I believe the socket is 13mm This gives a lot of space for the rear bank when you get to it:

Next, remove the silver beautay cover that sits on top of the intake manifold. 13mm socket.

After getting the beautay cover off, you'll want to remove the plug wires from the ignition coils that sit above the rear bank. Easy, just pop the connections off. The same goes for the plug boots. I left those in the plug holes as to avoid getting stuff in the plug holes. Take note of plug wire routing so you know what goes where when you button things back up. This is where that electrical tape came in handy for me.

Next, you'll want to remove the ignition coils. All of them are mounted on a metal plate. Four screws, two on the front and two on the rear, hold it down. 10mm socket. There's also 2 electrical connections per side on the left and right sides of the ignition coils. Make sure those come off when you remove the coils. More importantly, make sure they are all plugged in when you go to test your repair. Ask me how I know.

Re: HOW TO: Change the spark plugs on a 96 VIN Y DeVille

Since the plug connections are labeled on the coils, I did all of the plugs an once. Check yours before starting to determine if you can do the same.

The front bank is easy. They take some oomph to get loose at first, but all mine came out with good threads and the threads in the block were good.

With the coils and the strut brace out of the way, the rear bank is a BREEZE. If you're a vertically challenged individual, a stool may be handy. All I'm saying is that I'm 6'1 and I had no trouble getting to the rear bank. That being said, there was something in the way on the left side. Not sure what it is (HINT HINT ) but one 10mm bolt holds it down.

The wires didn't have the numbering that the factory plugs did,

...but a few quick length checks and a silver Sharpie cleared that up

Coat the first three threads with anti-seize, I've heard that's more than enough. Don't be gun-shy when reinstalling plugs, just go nice and slow. Center the plug socket in the hole and the plugs pretty much center themselves. Stop right after the plugs first really snug up. That way if you ever do this again it won't be a pain in the butt (The anti-seize helps too ).

Here's a before and after picture. It now comes as no surprise that she runs WAY better at any engine speed.

The old plugs have some oil near the thread base. O-ring seepage from the heads, and perfectly NORMAL. Carboned-up electrodes, also normal. Another typical old plug condition is the carbon tracking, apparently oil, near the base of the white part (I know, technical ). The plug wires usually have this as well (from what I've heard, and my plug boots smelled JUST like motor oil) so it's a good idea to change the wires too, even though it may seem excessive.